This diagram quiz is designed to assess your understanding about the "Nitrogen cycle". Choose the best answer from the four options given. When you've finished answering as many of the questions as you can, scroll down to the bottom of the page and check your answers by clicking 'Score'. Percentage score will be displayed along with right answers.

1. The major reservoir of Nitrogen is
atmosphere
soil
water
rocks
2. Biological Nitrogen fixation refers to the conversion of
atmospheric N2 to NO3- and NH3
atmospheric N2 to NO2
atmospheric N2 to NH3
atmospheric NH3 to NO33. Approximately 70% of all nitrogen fixed is through biological fixation. The nitrogen fixing bacterium that lives symbiotically in the roots nodules of leguminous plants labelled A is
Clostridium
Azotobacter
Rhizobium
Psuedomonas4. Free living nitrogen fixers in soil labelled B, that helps in N2 fixation include
Azotobacter and Clostridium
Anabaena and Nostoc
Beijerinckia and Klebsiella
All of the above5. The conversion of Ammonia (NH3) to nitrite (NO2-) and then to nitrate (NO3-), labelled C is called
Denitrification
Assimilation
Ammonification
Nitrification
6. Nitrite (NO2) is further oxidized and converted to nitrate (NO3) by a bacterium labelled D is
Nitrobacter
Pseudomonas
Acetobacter
Nitrosomonas7. The plants absorb nitrates (NO3) from the soil and use them for the synthesis of proteins. The process labelled E is called
nitrification
assimilation
ammonification
Denitrification8. The process labelled F where ammonium (NH4) is formed from amino acids by decomposers is
amination
nitrogen fixation
ammonification
nitrification
9. The process labelled G return part of fixed nitrogen back to the atmosphere by converting nitrates (NO3-) back to nitrogen gas (N2)is
denitrogen fixation
denitrification
nitrification
deamination
10. The bacteria involved in denitrification process include
Pseudomonas
Thiobacillus denitrificans
Micrococcus denitrificans
All of the above
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